<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>CSS3过渡</title>
<style>
	#box{ width:100px; height:100px; background:red; 
		transition:1s width; }
	#box:hover{ width:150px; height:150px; background:blue; }
</style>
</head>
<body>
<div id="box"></div>
</body>
</html>
